"Based on all the evidence and analysis presented in this report, I come to the conclusion that Officer Manney's use of force in this incident was justified self-defence and that defence cannot be reasonably overcome to establish a basis to charge Officer Manney with a crime," Milwaukee County district attorney John Chisholm said.

Mr Manney is at least the third white American police officer in the last month to avoid prosecution after shooting dead a black man.

The shooting occurred after the police officer responded to a call to check on the welfare of a man sleeping in a park in the city.

According to the police officer’s version of events, Mr Hamilton resisted an attempt by officer to search him.

The two are said to have exchanged punches before the rough sleeper somehow obtained the officer’s baton and hit him on the neck. The police officer then shot the man 14 times.